1. Field of the Invention
The present invention relates to a camera control unit that controls the capturing direction, zoom ratio, and so on of a video camera.
2. Description of the Related Art
With the recent spread of IP networks, videophone systems, remote monitoring systems, and the like, in which video and audio captured by cameras is transmitted across an IP network and viewed, are becoming commonplace. Furthermore, fiber-optic networks capable of instantly transmitting high-bandwidth data have also spread over the past several years, and various systems, which utilize such networks for the simultaneous distribution and viewing of images from a plurality of cameras, have appeared. There are even some such systems in which plural cameras are arranged and installed at certain set angles, shooting images across a wide field of view; the images are then displayed in plural remote displays, making it possible to simultaneously view all the images from that wide field of view.
There is, however, a limit to the number of cameras and displays that can be installed, and thus issues such as users desiring to shoot objects outside of the field of view, users desiring to zoom in on objects and shoot them, and so on arise even if plural cameras have been installed. Patent Document 1 (Japanese Unexamined Patent Publication H11-8843), described below, can be given as an example of a scheme that attempts to address these desires.
This related art provides a system in which, rather than using a wide-angle lens, plural cameras are arranged, shooting across a wide field of view at high resolution, the resultant of which is viewed on a plurality of displays, and the zoom ratios of each of the plural cameras are controlled. According to this related art, in a three-camera arrangement, the cameras installed on both sides undergo capturing direction (pan and tilt) control in addition to zoom control. This solves problems that arise when only zoom control is carried out on the plural cameras, such as overlap occurring in regions displayed between screens and the occurrence of regions that cannot be seen due to gaps in the display, and allows the images of plural cameras displayed on plural screens to be viewed seamlessly between those plural screens.
FIG. 19 is a diagram illustrating this related art. The camera control process according to the present related example shall be described with reference to FIG. 19. In FIG. 19, 100-1 to 100-3 indicate cameras, 110 indicates a camera control unit, and 120-1 to 120-3 indicate displays.
When a user manipulates an operational unit 111 to input a value specifying the overall angle of view at which the plural arranged cameras can shoot, an angle of view instruction generation unit 112 calculates the angles of view of each camera by dividing that value specifying the overall angle of view equally by three, and furthermore calculates the capturing directions of the two cameras 100-1 and 100-3 installed on both sides. The calculated angle of view information is passed to a zoom amount control unit 113, while the calculated capturing direction information is passed to a camera direction control unit 114. The zoom amount control unit 113 controls the zoom ratio of the plural cameras so that they take on the specified angle of view. Meanwhile, the camera direction control unit 114 controls the cameras on both sides so that they take on the respective specified capturing directions.
A camera control method of the camera control unit 110 shall be described with reference to FIGS. 20 and 21. FIG. 20 is a diagram illustrating the area being shot by the plural cameras and the appearance of the displays in which those camera images are being displayed. 200-1 to 200-3 indicate cameras, 210 indicates the area being shot by the cameras 200-1 to 200-3, and 220-1 to 220-3 indicate displays.
Here, the angle of view and capturing direction of the camera 200-2 are taken as the reference position. When the user uses the operational unit 111 to instruct an increase in the zoom ratio relative to that reference position, the angle of view instruction generation unit 112 raises the zoom ratios of all cameras together, and also rotates the cameras on both sides so as to draw closer to the capturing direction of the camera in the middle, performing control so that the areas between the cameras 220-1 and 220-2 and the areas between 220-2 and 220-3 do not experience gaps or overlaps in the display. Conversely, when the user uses the operational unit 111 to instruct a decrease the zoom ratio relative to the reference position, the angle of view instruction generation unit 112 lowers the zoom ratios of all cameras together, and also rotates the cameras on both sides so as to distance themselves from the capturing direction of the camera in the middle, performing control so that the areas between the cameras 220-1 and 220-2 and the areas between 220-2 and 220-3 do not experience gaps or overlaps in the display.
As described thus far, when the zoom ratio of plural arranged cameras is changed through user operations, controlling the capturing direction of the cameras in addition to the zoom ratios of the cameras eliminates overlaps and gaps between the plural screens on which the images are displayed, making it possible to display the images seamlessly.
However, if the related art is applied to, for example, a videoconference system such as that illustrated in FIG. 21, which photographs objects 310-1 and 310-2 and transmits the captured images to a remote location, the objects are captured in a manner in which they cross the borders of the plural arranged screens, as illustrated by screens 220-1 to 220-3 in FIG. 21. The result is that even if control can be performed so that the regions displayed on the screens do not experience overlaps and gaps between the plural screens, the object appears to be hidden behind the frame of the screen. This in turn results in visual abnormalities experience by the viewer, in the sense that the object cannot be viewed in detail.
In particular, the recent spread of large-screen displays has led to the appearance of videoconference systems that display objects at life size, giving viewers a high sense of presence, as if the object, which is actually at a remote location, is present before their very eyes. Such videoconference systems demand that objects are captured as close to life size as possible, and thus if a user simply adjusts the zoom ratio so that the entire object is captured without crossing the screen borders, the object will appear too small. Meanwhile, if the zoom ratio is controlled to the widest angle possible, it may not be possible to capture all objects in a manner in which they do not cross the screens.
Furthermore, even if, for example, the user can control the capturing directions of all the cameras in addition to the zoom ratios of the cameras, it is extremely difficult to determine capturing directions and zoom ratios as which all objects can be captured without crossing screen borders while also being shot as close to life size as possible.